used search engines (PDF, PPT, Word, excel, txt)

Today found a very good PDF using search engines, and share and to make a simple evaluation analysis!
1, PDF Google
Today, the PDF found easy to use search engine, to provide professional PDF file search, support in English, to share the results of three ways: download, browse, code, and provide the same keywords doc files, ppt files, excel files, pdf files, txt file the entry of professional search that is entered once keywords, you can get five kinds of documents the professional search! Search fast, comprehensive, very good use.
Website: http://www.pdfgoogle.com/

2, paper search
Paper search is a professional PDF file search engine, there are 500,000,000 included in this paper, to support Chinese and English keywords, support for pdf, word, ppt, excel documents in various formats such as search, interface, fresh, comprehensive search results and content strong, and option to view or download the search speed quickly, and the pdf google capabilities to fight some one.
Website: http://www.paper-search-engine.com/

3, PDF ebook
Ebook seek is a good special search engine offers free PDF, PPT, and doc files search services, especially PDF search service is a major bright spot. The databases, with the former two are evenly matched, on the user's operational flexibility! Can be in English and Chinese search, but search speed is sometimes too slow.
Website: http://www.ebook-seek-engine.com/

4, pdf engine
Pdf engine to Chinese search, the search results page displays a large amount of reduction of tabbed browsing tedious. However, most regrettably slow, or even not open phenomenon. But speed is not the lack of a good search engine, the basic quality!
Website: http://www.pdf-seek-engine.com/

5, Google PDF
Search Google PDF can be in English and Chinese, can search PDF, PPT, Word, excel, txt a variety of text formats, the search results page displays a large amount of red tape to reduce tabbed browsing, the search speed.
Website: http://www.manydoc.com